Global evaluation and calibration of a passive air sampler for gaseous mercury Atmospheric Chemistry and Physics DOI 10.5194/acp-18-5905-2018 26 April 2018 A new passive air sampler for gaseous mercury was tested at 20 sites on four continents. These sites have in common that they use the state-of-the-art active air sampling technique for gaseous mercury on a continuous basis and therefore allow for an evaluation and calibration of the passive sampler. The sampler proved to work exceptionally well, with a precision and accuracy on par with the active instrument and better than what has previously been achieved with passive samplers. Read more
Novel pathway of SO2 oxidation in the atmosphere: reactions with monoterpene ozonolysis intermediates and secondary organic aerosol Atmospheric Chemistry and Physics DOI 10.5194/acp-18-5549-2018 24 April 2018 Synergistic effects between SOA formation and SO2 oxidation through Criegee chemistry and reactive uptake by organic peroxides were observed. The relative importance of these two pathways (Criegee vs. peroxide) varies with relative humidity. The latter SO2 loss mechanism to organic peroxides in SOA has not previously been identified. Our results suggest a new pathway of atmospheric SO2 oxidation, which may contribute to the missing mechanisms of high-sulfate production in the polluted areas. Read more
Using satellite measurements of N2O to remove dynamical variability from HCl measurements Atmospheric Chemistry and Physics DOI 10.5194/acp-18-5691-2018 24 April 2018 Detecting trends in short data sets of stratospheric molecules is difficult because of variability due to dynamical fluctuations. We suggest that one way around this difficulty is using the measurements of one molecule to remove dynamical variability from the measurements of another molecule. We illustrate this using Aura MLS measurements of N2O to help us sort out issues in the determination of trends in HCl. This shows that HCl is decreasing throughout the middle stratosphere as expected. Read more
The influence of atmospheric grid resolution in a climate model-forced ice sheet simulation The Cryosphere DOI 10.5194/tc-12-1499-2018 23 April 2018 Coupled climate–ice sheet simulations have been growing in popularity in recent years. Experiments of this type are however challenging as ice sheets evolve over multi-millennial timescales, which is beyond the practical integration limit of most Earth system models. A common method to increase model throughput is to trade resolution for computational efficiency (compromise accuracy for speed). Here we analyze how the resolution of an atmospheric general circulation model (AGCM) influences the simulation quality in a stand-alone ice sheet model. Four identical AGCM simulations of the Last Glacial Maximum (LGM) were run at different horizontal resolutions: T85 (1.4∘), T42 (2.8∘), T31 (3.8∘), and T21 (5.6∘). These simulations were subsequently used as forcing of an ice sheet model. Read more
Considering the future of anthropogenic gas-phase organic compound emissions and the increasing influence of non-combustion sources on urban air quality Atmospheric Chemistry and Physics DOI 10.5194/acp-18-5391-2018 20 April 2018 Following decades of successful regulatory policies focused on combustion-related sources (e.g. motor vehicles), emissions from non-combustion sources have become increasingly important for urban air quality. Using multiple approaches, we demonstrate that emissions from consumer, commercial, and industrial products and materials have become prominent contributors to the formation of photochemical smog (i.e. secondary organic particulate matter and ozone) and its associated health effects. Read more
Moving beyond the age–depth model paradigm in deep-sea palaeoclimate archives: dual radiocarbon and stable isotope analysis on single foraminifera Climate of the Past DOI 10.5194/cp-14-515-2018 20 April 2018 Palaeoclimate reconstructions from deep-sea sediment archives provide valuable insight into past rapid climate change, but only a small proportion of the ocean is suitable for such reconstructions using the existing state of the art, i.e. the age–depth approach. We use dual radiocarbon (14C) and stable isotope analysis on single foraminifera to bypass the long-standing age–depth approach, thus facilitating past ocean chemistry reconstructions from vast, previously untapped ocean areas. Read more
Mercury distribution and transport in the North Atlantic Ocean along the Geotraces-GA01 transect Biogeosciences DOI 10.5194/bg-15-2309-2018 19 April 2018 We first report the mercury distribution in the water section across the subpolar and subtropical gyres of the North Atlantic Ocean (GEOTRACES-GA01 transect). It allows the characterisation of various seawater types in terms of mercury content and the quantification of mercury transport associated with the Atlantic Meridional Overturning Circulation. It shows the nutrient-like biogeochemical behaviour of mercury in this ocean. Read more
Interannual drivers of the seasonal cycle of CO2 in the Southern Ocean Biogeosciences DOI 10.5194/bg-15-2361-2018 19 April 2018 The Southern Ocean accounts for a large portion of the variability in oceanic CO2 uptake. However, the drivers of these changes are not understood due to a lack of observations. In this study, we used an ensemble of gap-filling methods to estimate surface CO2. We found that winter was a more important driver of longer-term variability driven by changes in wind stress. Summer variability of CO2 was driven primarily by increases in primary production. Read more
Brief communication: Loss of life due to Hurricane Harvey Natural Hazards and Earth System Sciences DOI 10.5194/nhess-18-1073-2018 19 April 2018 An analysis was made of the loss of life directly caused by Hurricane Harvey. Information was collected for 70 fatalities that occurred directly due to the event. Most of the fatalities occurred in the greater Houston area, which was most severely affected by extreme rainfall and heavy flooding. The majority of fatalities in this area were recovered outside the designated 100- and 500-year flood zones. Most fatalities occurred due to drowning (81 %), particularly in and around vehicles. Read more
Regional evapotranspiration from an image-based implementation of the Surface Temperature Initiated Closure (STIC1.2) model and its validation across an aridity gradient in the conterminous US Hydrology and Earth System Sciences DOI 10.5194/hess-22-2311-2018 18 April 2018 We report the first ever regional-scale implementation of the Surface Temperature Initiated Closure (STIC1.2) model for mapping evapotranspiration (ET) using MODIS land surface and gridded climate datasets to overcome the existing uncertainties in aerodynamic temperature and conductance estimation in global ET models. Validation and intercomparison with SEBS and MOD16 products across an aridity gradient in the US manifested better ET mapping potential of STIC1.2 in different climates and biomes. Read more
